I-III-VI2 compounds of the CuInxGa(1-x)SeyS(2-y) type (where x is substantially between 0 and 1 and y is substantially between 0 and 2) are regarded as very promising and could constitute the next generation of thin-film photovoltaic cells. These compounds have a wide direct bandgap of between 1.05 and 1.6 eV, which allows solar radiation in the visible to be strongly absorbed.
Record photovoltaic conversion efficiencies have been achieved by preparing thin films by evaporation on small areas. However, evaporation is difficult to adapt to the industrial scale because of problems of nonuniformity and low utilization of raw materials. Sputtering is better suited to large areas, but it requires very expensive vacuum equipment and precursor targets.
There is therefore a real need for alternative, low-cost atmospheric-pressure, techniques. The technique of thin-film deposition by electrochemistry, in particular by electrolysis, appears to be a very attractive alternative. The advantages of this deposition technique are numerous, and in particular the following:                deposition at ambient temperature and ambient pressure in an electrolysis bath;        possibility of handling large areas with high uniformity;        ease of implementation;        low installation and raw material costs (no special forming operation, high level of material utilization); and        great variety of possible deposit shapes due to the localized nature of the deposit on the substrate.        
Despite extensive research in this field, the difficulties encountered relate to the control of the quality of the electrodeposited precursors (composition and morphology) and the efficiency of the electrolysis bath after several successive depositions.